JP3522489B2 - Adhesive for electroless plating used for printed wiring boards and printed wiring boards - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive for electroless plating and a printed wiring board, and more particularly to forming an adhesive layer for electroless plating which has excellent translucency and is free of bubbles and undulations. This is a proposal for an effective adhesive.

[0002]

2. Description of the Related Art In recent years, electronic devices have become smaller and faster as the electronics industry advances. Therefore, high density and high reliability by fine patterns are also required for printed boards and wiring boards on which LSIs are mounted.

The additive method is one of the conventional methods for manufacturing a printed wiring board that meets the requirements of this type. This additive method applies an electroless plating adhesive to the substrate surface to form an adhesive layer, roughens the surface of this adhesive layer for electroless plating, and then performs electroless plating to form a conductor. Is the way to do it.

In this method, since the conductor circuit is formed by electroless plating, wiring having a higher density and a higher pattern accuracy can be formed easily and at a lower cost than the etched foil method (subtractive method) in which a pattern is formed by etching. There is an advantage that it can be manufactured. Moreover, since this method firmly adheres the conductor circuit to the roughened adhesive layer, excellent bondability is ensured between the two.
It is characterized in that the conductor circuit is difficult to peel off from the adhesive layer.

As a conventional printed wiring board based on such an additive method, there are the following proposals regarding an adhesive for electroless plating. For example, JP-A-61-276875
No. 2, JP-A-2-188992, USP 5055321, etc.
There has been proposed a printed wiring board using a photosensitive adhesive for electroless plating, which is obtained by dispersing a heat-resistant resin fine powder in a photosensitive resin matrix.

On the other hand, in the case of a printed wiring board using an adhesive for electroless plating, good leveling property and defoaming property of the adhesive are required in order to obtain wiring with high pattern accuracy even if it is multilayered. Is. The reason is that if the surface of the adhesive layer is not smooth, it is difficult to mount IC chips, etc.
This is because if air bubbles are present in the adhesive layer, water may accumulate in the air bubbles and cause cracks.

Regarding this point, an adhesive agent to which an antifoaming agent or a leveling agent is added can be considered. However, the adhesive layer to which the defoaming agent or the leveling agent is added has a drawback that the light-transmitting property is lowered and it is impossible to form a good hole even by exposure or laser irradiation.

[0008]

SUMMARY OF THE INVENTION Therefore, the main object of the present invention is to provide an adhesive for electroless plating, which is excellent in leveling property and defoaming property without deteriorating the translucency of the adhesive layer. To do. Another object of the present invention is to provide a printed wiring board having an adhesive layer for electroless plating, which has excellent translucency and is free of bubbles and undulations.

[0009]

[Means for Solving the Problems] The inventors of the present invention have conducted earnest research toward achieving the above object. As a result, the following findings were obtained. ． It does not devitrify even if silicone oil is dissolved in an organic solvent in which the resin is dissolved. ． To improve the strength, a thermoplastic resin is added to the resin matrix, and NMP (N-methylpyrrolidone) is used as an organic solvent to improve the compatibility of the composite resin adhesive for electroless plating. Also in this case, devitrification will not occur if silicone oil having a specific structure is used. ． Silicone oil has the effect of improving the strength of the resin.

The adhesive for electroless plating of the present invention developed based on such knowledge is characterized by having the following constitution. (1) The adhesive for electroless plating used in the printed wiring board of the present invention is an uncured product in which a cured heat-resistant resin particle that is soluble in an acid or an oxidizing agent is hardly soluble in an acid or an oxidizing agent by the curing treatment. In the adhesive for electroless plating dispersed in the heat-resistant resin matrix, the heat-resistant resin matrix contains silicone oil in an amount of more than 5% by weight and 50% by weight or less. .

In the adhesive for electroless plating according to the above (1), the silicone oil has a terminal group whose epoxy group, polyoxyalkylene group, amino-containing group, carboxy-containing group, fatty acid-containing group and alcohol. It is desirable that it be modified with at least one functional group selected from the containing groups. Further, this silicone oil is preferably a polyether-modified silicone oil having a polyethylene oxide structure or a polypropylene oxide structure. Further, it is desirable that this silicone oil has the structural formula shown in the following (Chemical formula 1). (Chemical formula 1)

The printed wiring board of the present invention is characterized by having the following structure. (2) The printed wiring board of the present invention has, on the substrate, a surface-roughened cured electroless plating adhesive layer, and a conductor circuit is provided on the roughened surface of the adhesive layer surface. In the formed printed wiring board, the adhesive layer is a cured heat-resistant resin soluble in an acid or an oxidant in an uncured heat-resistant resin matrix that is hardly soluble in an acid or an oxidant by the curing treatment. It consists of an adhesive in which particles are dispersed, and the heat-resistant resin matrix contains more than 5% by weight.
It is characterized by containing 50% by weight or less of silicone oil.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The adhesive for electroless plating used in the printed wiring board of the present invention comprises an uncured heat-resistant resin matrix which is hardly soluble in an acid or an oxidant by a curing treatment. It is characterized in that it contains more than 5% by weight and 50% by weight or less of silicone oil.

This silicone oil is a linear molecule having a siloxane bond (-Si-O) _n- and exhibits fluidity at room temperature. Therefore, when silicone oil is added to the uncured heat-resistant resin matrix containing an organic solvent, the silicone oil is finely dispersed and contained in the matrix. As a result, the adhesive layer formed by using the adhesive for electroless plating containing such silicone oil does not appear to devitrify even if silicone oil is present in the matrix, and laser perforation, exposure and development are performed. The holes can be satisfactorily drilled by the treatment, and the via hole can be reliably formed.

As the heat-resistant resin containing the silicone oil, for example, a resin composite of a thermosetting resin and a thermoplastic resin is used, and N-methylpyrrolidone (N
When MP) is used, in such a composite resin system, the compatibility of the silicone oil decreases, the dispersed particles of the silicone oil become large, and devitrification easily occurs. In this respect, a silicone oil having an ethylene oxide structure or a propylene oxide structure is suitable because it has a function of preventing devitrification even in the above composite resin system. The reason for this is not clear, and it is presumed that ethylene oxide and propylene oxide have excellent affinity with the composite resin and NMP.

As such a silicone oil, the one having the structural formula shown in the following (Chemical formula 1) is most suitable. (Chemical formula 1) Here, n is 1 to 5, m is 1 to 14, x is 1 to 80, and y is 1
It is desirable to be about 74. The optimum value is n = 1, m
= 7, x = 40, y = 37.

Further, the silicone oil has a function that fine particles of the silicone oil penetrate into the bubble film, and cracks are generated from this point to eliminate bubbles in the interlayer insulating agent. Furthermore, since this silicone oil is finely dispersed in an island shape in the heat resistant resin matrix of the interlayer insulating agent, it also has an effect of improving the fracture strength (toughness) of the heat resistant resin matrix.

In particular, as the silicone oil capable of improving the strength of the resin, the terminal group thereof is selected from the group consisting of epoxy group, polyoxyalkylene group, amino-containing group, carboxy-containing group, fatty acid-containing group and alcohol-containing group. It is desirable that it is modified with at least one functional group. For example, epoxy group-modified silicone oils include KF101, KF102 and KF manufactured by Shin-Etsu Chemical.
There are 105 etc. Examples of the polyoxyalkylene group-modified silicone oil include KF351 and KF353 manufactured by Shin-Etsu Chemical. Examples of amino-containing group-modified silicone oils include Shin-Etsu Chemical's KF393 and KF861. Examples of the carboxy-containing group-modified silicone oil include X-22-3701E manufactured by Shin-Etsu Chemical. Examples of the fatty acid-containing modified base silicone oil include KF910 manufactured by Shin-Etsu Chemical. As the alcohol-containing group-modified silicone oil,
There is KF851 manufactured by Shin-Etsu Chemical.

As an example, the structural formula of epoxy-modified silicone oil is shown in the following (Chemical formula 2).

[Chemical 2]

As explained above, the silicone oil contained in the adhesive has both a function as an antifoaming agent and a function as an additive for improving the resin strength, but in particular, its content is 0.1-5 wt. %, It mainly acts as an antifoaming agent, and when it exceeds 5% by weight and 50% by weight or less,
It mainly acts as an additive for improving the resin strength.

In the adhesive for electroless plating of the present invention,
The hardened heat-resistant resin particles that are soluble in the acid or oxidizing agent that make up the adhesive have an average particle size of 10 μm.
The following heat-resistant resin powder, agglomerated particles obtained by aggregating heat-resistant resin powder having an average particle size of 2 μm or less, average particle size 2 to 10 μm
Of heat-resistant powder resin powder and heat-resistant resin powder having an average particle diameter of 2 μm or less, either heat-resistant resin powder having an average particle diameter of 2 μm or less or inorganic powder on the surface of the heat-resistant resin powder having an average particle diameter of 2 μm to 10 μm It is desirable to be selected from among pseudo particles formed by adhering at least one kind thereof. This is because they can form more complex anchors.

Epoxy resins, amino resins (melamine resins, gunaamine resins, urea resins), polyester resins and the like are preferably used as the heat resistant resin particles. In particular, a resin obtained by curing a bisphenol A type epoxy resin with an amine curing agent is desirable. This is because these resin particles are easily decomposed or dissolved in an acid or an oxidizing agent and easily form a clear anchor.

In the adhesive for electroless plating of the present invention,
As the uncured heat-resistant resin matrix that becomes hardly soluble in acid or oxidizing agent by the curing treatment, a thermosetting resin,
A photosensitized thermosetting resin or a composite of a photosensitized thermosetting resin and a thermoplastic resin can be used. The photosensitization is performed because the via holes can be easily formed by the exposure and development processes. Further, the reason why the resin is compounded with the thermoplastic resin is that by improving the toughness of the resin, the peel strength of the conductor circuit is improved, and the occurrence of cracks in the via hole portion due to the heat cycle can be prevented. Specifically, a polyimide resin, an epoxy resin, an epoxy acrylate obtained by reacting an epoxy resin with acrylic acid or methacrylic acid, or a composite of epoxy acrylate and polyether sulfone is preferable.

The epoxy resin used as the resin matrix is a cresol novolac type epoxy resin or a phenol novolac type epoxy resin cured with an imidazole curing agent or an acid anhydride, or an alicyclic epoxy resin. preferable. This is because these cured resins are hardly soluble in acids and oxidants and have excellent base resistance. The electroless plating solution is strongly basic, and basic resistance is an essential property of the adhesive for electroless plating.

As the alicyclic epoxy resin, Araldite CY179 (manufactured by Ciba Geigy), EPICLON HP-7200
(Made by Dainippon Ink and Chemicals, Inc.) is preferable. EPIC of these
The structural formula of LONHP-7200 is shown in Chemical formula 3.

[Chemical 3]

When this alicyclic epoxy resin is mixed with silicone oil, the mixing ratio is preferably (weight of alicyclic epoxy resin / silicone oil) = 9/1 to 8/2. The reason for this is that if the silicone oil is too much, it will be difficult to mix with the alicyclic epoxy resin,
On the other hand, if the amount of silicone oil is small, it becomes difficult to improve the strength.

The above-described adhesive for electroless plating according to the present invention may be applied to a substrate as it is, or it may be impregnated with glass cloth and dried to form a B-stage to form a prepreg. Alternatively, it may be applied to a base film such as polyethylene terephthalate or polypropylene and dried to form a B stage, which may be formed into a film. Further, it is possible to form it into a substrate shape.

A dye or pigment may be added to the adhesive for electroless plating. Further, the resin used in the adhesive for electroless plating may be halogenated to make it flame-retardant.

Next, a method for producing a printed wiring board using the adhesive for electroless plating of the present invention will be described. The method according to this description is a so-called full-additive method, but a method called a so-called semi-additive method can also be adopted in the present invention.

(1) First, a wiring board having an inner layer copper pattern formed on the surface of a core board is manufactured. The copper pattern is formed on the core substrate by etching the copper clad laminate, or by using a glass epoxy substrate or a polyimide substrate,
There is a method in which an adhesive layer for electroless plating is formed on a substrate such as a ceramic substrate or a metal substrate, the surface of the adhesive layer is roughened to form a roughened surface, and electroless plating is performed on the roughened surface. Further, if necessary, an adhesive layer for electroless plating is formed on the wiring board, an opening for a via hole is provided in this layer, the surface of the layer is roughened, and electroless plating is performed there to form a copper pattern and a via. By repeating the step of forming holes, a multilayer wiring board can be obtained. A through hole can be formed in the core substrate, and the front and back wiring layers can be electrically connected through the through hole.

(2) Next, an adhesive layer for electroless plating according to the present invention is formed on the wiring board prepared in (1) above. (3) After drying the adhesive layer for electroless plating, an opening for forming a via hole is provided if necessary. At this time,
In the case of a photosensitive resin, an opening for forming a via hole is formed in the adhesive layer by heat-curing after exposure and development, and in the case of a thermosetting resin, heat-curing and then laser processing. Set up a section.

(4) Next, the heat-resistant resin particles existing on the surface of the cured adhesive layer are dissolved and removed with an acid or an oxidizing agent to roughen the surface of the adhesive layer. Here, examples of the acid include phosphoric acid, hydrochloric acid, sulfuric acid, and organic acids such as formic acid and acetic acid, and it is particularly preferable to use organic acids. This is because when the roughening treatment is performed, the metal conductor layer exposed from the via hole is unlikely to corrode. Chromic acid or permanganate (such as potassium permanganate) is preferably used as the oxidizing agent.

(5) Next, catalyst nuclei are applied to the wiring board whose surface of the adhesive layer has been roughened. It is desirable to use a noble metal ion, a noble metal colloid, or the like for providing the catalyst nucleus, and in general, palladium chloride or a palladium colloid is used. In addition, it is desirable to perform heat treatment to fix the catalyst nuclei. Palladium is preferable as such a catalyst nucleus.

(6) Next, a plating resist is formed on the wiring board to which the catalyst nucleus has been added. As the plating resist composition, a commercially available product can be used, but a composition comprising cresol novolac, an acrylate of a phenol novolac type epoxy resin and an imidazole curing agent is particularly preferable.

(7) Then, electroless plating is applied to the non-plating resist forming portion to form a conductor circuit and via holes to manufacture a printed wiring board.

The printed wiring board according to the present invention manufactured in this manner has "a surface-roughened and cured adhesive layer for electroless plating, and the surface of the adhesive layer. In a printed wiring board in which a conductor circuit is formed on the roughened surface of the adhesive layer, the adhesive layer is added to the acid or the oxidant in the uncured heat-resistant resin matrix that is hardly soluble in the acid or the oxidant by the curing treatment. A printed wiring board comprising an adhesive agent in which soluble and hardened heat-resistant resin particles are dispersed, and the heat-resistant resin matrix contains silicone oil.

This printed wiring board has a roughening layer formed by dissolving and removing the heat-resistant resin particles existing on the surface of the adhesive layer, and the roughening layer has a takotsubo-shaped anchor. Therefore, in this printed wiring board, since the anchor is filled with the electroless plated film of the conductor, the adhesion strength of the conductor is excellent.

Further, this printed wiring board contains silicone oil in the heat resistant resin matrix constituting the adhesive layer. Since this silicone oil is finely dispersed in the matrix, it does not appear to devitrify the adhesive layer. Therefore, in the printed wiring board according to the present invention, it is possible to satisfactorily perform punching by laser, exposure, and development, and it is possible to surely form a via hole. In this silicone oil, the fine particles penetrate into the bubble film, and cracks are generated from this point to eliminate bubbles in the interlayer insulating agent. Therefore, in the printed wiring board according to the present invention, voids are not generated in the adhesive layer, and water does not collect even under high temperature and high humidity conditions, and thus cracks are less likely to occur. This silicone oil is
Since it is finely dispersed in an island shape in the heat-resistant resin matrix of the adhesive layer, it has an effect of improving the fracture strength (toughness) of the heat-resistant resin matrix. Therefore, the printed wiring board according to the present invention can suppress cracks generated in the adhesive layer between layers starting from the boundary between the plating resist and the conductor circuit due to the heat cycle.

[0039]

【Example】

[Synthesis of Silicone Oil A] (1) Add 10 parts by weight of 0.1N hydrochloric acid and water to alkoxysilane consisting of 8.12 parts by weight of dimethylmethoxysilane and 1.38 parts by weight of methylchloroethylmethoxysilane, stir at 50 ° C., and leave for 24 hours. did. (2) After adding 1N KOH, 17.6 parts by weight of ethylene oxide was added, and the mixture was stirred at 50 ° C. and then left for 8 hours. (3) After further adding 1N KOH, 21.5 parts by weight of propylene oxide was added, and the mixture was stirred at 50 ° C. and left for 8 hours.

With respect to the silicone oil thus synthesized, ¹ H-NMR, ¹³ C-NMR and IR spectra were measured. The measurement results are shown in FIGS. FT
-IR uses PERKIN ELMER 1650 and uses transmission method (KR
S-5). NMR is JEOL EX
-400 is used, the observation frequency is 400 MHz for ¹ H, ¹³ C
Is 100 MHz, pulse width 45 °, measurement solvent is deuterated chloroform, chemical shift standard is 7.25 ppm at ¹ H, 7 at ¹³ C
It is 7.05 ppm. The measurement temperature is room temperature. From these figures, the silicone oil synthesized here was n = 1, m = 7, x = 40, y = 37 in the structural formula shown in (Chemical Formula 1).

[Preparation of Adhesive B-1 for Electroless Plating] D
35 parts by weight of 25% acrylate of cresol novolac type epoxy resin (manufactured by Nippon Kayaku, molecular weight 2500) dissolved in MDG (diethylene glycol dimethyl ether), 12 parts by weight of polyether sulfone (PES), imidazole curing agent (manufactured by Shikoku Kasei, Product name: 2E4MZ-CN) 2 parts by weight,
Caprolactone modified tris (acryloxyethyl) isocyanurate (Toagosei, trade name: Aronix M325) 4 parts by weight, benzophenone (Kanto Kagaku) 2 parts by weight as a photoinitiator, as a photosensitizer Michler's ketone (manufactured by Kanto Kagaku Co., Ltd.) of 0.2 parts by weight is mixed, and an epoxy resin particle (manufactured by Sanyo Kasei Co., Ltd., trade name: Polymer Pole) having an average particle size of 3.0 μm is added to the mixture, and 10.3 parts by weight of the mixture are mixed. After mixing 3.09 parts by weight of 0.5 μm and 0.5 part by weight of the synthesized silicone oil of A, further mixing while adding NMP, and adjusting the viscosity to 7 Pa · s with a homodisper stirrer, and then using 3 rolls The mixture was kneaded to obtain an adhesive for electroless plating.

[Manufacture of Printed Wiring Board] (Example 1) (1) 18 μm on both sides of a substrate 1 made of glass epoxy resin or BT (bismaleimide triazine) resin having a thickness of 1 mm
A copper clad laminate having m copper foils 8 laminated thereon was used as a starting material (see FIG. 1). This copper clad laminate was drilled, electroless plated, and patterned to form inner layer copper patterns 4 and through holes 9 on both sides of the substrate 1.

(2) On the other hand, bisphenol F type epoxy monomer (Made by Yuka Shell, molecular weight 310, trade name: YL983U)
100 parts by weight, 6 parts by weight of an imidazole curing agent (manufactured by Shikoku Kasei, trade name: 2E4MZ-CN), 1.5 parts by weight of an antifoaming agent (manufactured by San Nopco, trade name: Perenol S4) are mixed, and the mixture is further mixed. On the other hand, SiO ₂ spherical particles with an average particle size of 1.6 μm coated with a silane coupling agent on the surface (manufactured by Admatech, CRS 1101-CE, where the maximum particle size is less than the thickness (15 μm) of the inner layer copper pattern described later). By mixing 170 parts by weight and kneading with 3 rolls, the viscosity of the mixture is 45,000 ～ 49,000 at 23 ± 1 ℃.
Adjusted to cps, resin filler for smoothing the substrate surface 10
Got This resin filler is solventless. If a resin filler containing a solvent is used, the solvent volatilizes from the resin filler layer when the interlayer agent is applied and heated / dried in a later step, and the space between the resin filler layer and the interlayer material is reduced. This is because peeling occurs.

(3) The substrate on which the inner layer copper pattern 4 was formed was washed with water and dried, and then NaOH (10 g / l), NaClO ₂ (40 g
/ L), Na ₃ PO ₄ (6 g / l) in oxidation bath (blackening bath), NaOH
(10 g / l) and NaBH ₄ (6 g / l) were used as a reducing bath, and a roughening layer 11 was provided on the entire surfaces of the inner layer conductor circuit 4 and the through holes 9 (see FIG. 2).

(4) The resin filler 10 obtained in the above (2) is applied to one surface of the substrate provided with the roughening layer using a roll coater, so that the inner conductor circuits 4 or the through holes 9 are exposed.
It is filled inside and temporarily hardened at 120 ° C for 20 minutes. Similarly, on the other side, the resin filler 10 is filled between the inner layer conductor circuits 4 or through holes 9 and temporarily hardened at 120 ° C for 20 minutes. (See FIG. 3).

(5) The surface of the inner layer copper pattern 4 and the through hole 9 are polished on one surface of the substrate which has been subjected to the treatment of (4) above by belt sander polishing using # 600 belt polishing paper (manufactured by Sankyo Rikagaku). Polishing was performed so that the resin filler 10 did not remain on the land surface, and then buffing was performed to remove scratches due to the belt sander polishing. Such a series of polishing was similarly performed on the other surface of the substrate (see FIG. 4). Then 100 ℃ for 1 hour, 120 ℃ for 3 hours, 150 ℃
The resin filler 10 was completely cured by heat treatment for 1 hour at 180 ° C. for 7 hours.

In this way, the surface layer portion of the resin filler 10 filled in the through holes 9 and the like and the roughening layer 11 on the upper surface of the inner conductor circuit 4 are removed to smooth both sides of the substrate,
A wiring board in which 10 and the side surface of the inner-layer conductor circuit 4 firmly adhere to each other via the roughening layer 11, and the inner wall surface of the through hole 9 and the resin filler 10 firmly adhere to each other via the roughening layer 11 Obtained. That is, by this step, the surface of the resin filler 10 and the surface of the inner layer copper pattern 4 are flush with each other. Here, the Tg point of the filled cured resin is 155.6 ° C, and the linear thermal expansion coefficient is 44.5 × 10 ^-6 /
It was ℃.

(6) The thickness of 2.5 μm on the upper surface of the land of the inner layer conductor circuit 4 and the through hole 9 exposed by the treatment of the above (5)
The roughened layer (uneven layer) 11 made of Cu-Ni-P alloy was formed, and a Sn layer having a thickness of 0.3 μm was further formed on the surface of the roughened layer 11 (see FIG. 5, however, regarding the Sn layer). Is not shown). The formation method is as follows. That is, the substrate is acid-degreased and soft-etched, and then treated with a catalyst solution consisting of palladium chloride and an organic acid to impart a Pd catalyst, and after activating this catalyst, copper sulfate 8 g / l, nickel sulfate 0.6 g / l, citric acid 15 g / l, sodium hypophosphite 29 g / l, boric acid 31 g / l, surfactant 0.1
Plating was carried out in an electroless plating bath consisting of g / l and pH = 9 to form a roughened layer 11 of Cu-Ni-P alloy on the upper surface of the copper conductor circuit 4 and the upper surface of the land of the through hole 9. Then,
Tin borofluoride 0.1 mol / l, thiourea 1.0 mol / l, temperature
A Cu—Sn substitution reaction was performed under the conditions of 50 ° C. and pH = 1.2 to form a Sn layer having a thickness of 0.3 μm on the surface of the roughened layer 11 (Sn layer is not shown).

(7) 25% of cresol novolac type epoxy resin (Nippon Kayaku, molecular weight 2500) dissolved in DMDG
35 parts by weight of acrylate, 12 parts by weight of polyether sulfone (manufactured by Mitsui Toatsu, trade name: PES1010P), 2 parts by weight of imidazole curing agent (manufactured by Shikoku Kasei, trade name: 2E4MZ-CN), and caprolactone which is a photosensitive monomer. Modified tris (acryloxyethyl) isocyanurate (manufactured by Toagosei,
Trade name: Aronix M325) 4 parts by weight, benzophenone (manufactured by Kanto Kagaku) as a photoinitiator, 2 parts by weight of Michler's ketone (manufactured by Kanto Kagaku) as a photosensitizer, and 0.2 parts by weight of these are mixed. Epoxy resin particles (Sanyo Kasei, trade name: Polymer Pole) average particle size 0.5 μm
12.0 parts by weight of A and 0.5 parts by weight of silicone oil A, and then NMP while mixing,
Interlayer insulation with viscosity of 1.5 Pas and 7.0 Pas (lower layer)
Got

(8) The interlayer insulating agent (lower layer) having a viscosity of 7.0 Pa · s obtained in (7) above was applied to both surfaces of the substrate in (6) above with a roll coater and left standing for 20 minutes in a horizontal state. 60 ℃
And dried to form the insulating agent layer 2a. Furthermore, apply the adhesive of B-1 on both sides of the substrate, leave it in a horizontal state for 20 minutes, and then dry it at 60 ° C for 30 minutes to obtain an adhesive layer with a thickness of 60 μm.
2b was formed (see Figure 6).

(9) Photomask films printed with 100 μmφ black circles are adhered to both sides of the substrate on which the insulating layer 2a and the adhesive layer 2b are formed.
It was exposed at / cm ² . Then, this is spray-developed with a DMTG solution, and the substrate is further subjected to an ultra-high pressure mercury lamp.
A 100 μmφ opening with excellent dimensional accuracy equivalent to that of a photomask film (opening 6 for via hole formation) by exposing at 00 mJ / cm ² and heating at 100 ° C for 1 hour and then at 150 ° C for 5 hours. A resin insulating layer 2 having a thickness of 50 μm was formed (see FIG. 7).

(10) The substrate in which the openings are formed is dipped in chromic acid for 2 minutes to dissolve and remove the epoxy resin particles on the surface of the adhesive layer 2b, thereby making the surface of the resin insulating layer 2 a rough surface. Then, it was immersed in a neutralizing solution (made by Shipley) and washed with water (see FIG. 8). Further, a palladium catalyst (manufactured by Atotech Co., Ltd.) was applied to the surface of the substrate that had been roughened (roughening depth 6 μm) to attach catalyst nuclei to the surface of the resin insulating layer 2 and the via hole openings 6. .

(11) On the other hand, 40% by weight dissolved in DMDG
Cresol novolac type epoxy resin (manufactured by Nippon Kayaku)
100 parts by weight of a photosensitizing oligomer (molecular weight 4000) obtained by acrylation of 50% of epoxy groups, and 20% by weight of bisphenol A type epoxy resin (produced by Yuka Shell, trade name: Epicoat 1001) dissolved in methyl ethyl ketone 32 parts by weight, imidazole curing agent (manufactured by Shikoku Kasei, trade name: 2E4MZ
-CN) 3.4 parts by weight, polyvalent acrylic monomer which is a photosensitive monomer (Nippon Kayaku, trade name: R604) 6.4 parts by weight,
Similarly, 3.2 parts by weight of a polyvalent acrylic monomer (Kyoeisha Chemical Co., Ltd., trade name: DPE6A), which is also a photosensitive monomer, is mixed, and 100 parts by weight of the mixture is further mixed with a leveling agent (Kyoeisha Chemical Co., Ltd., trade name: Polyflow No. 75) 0.5 parts by weight were mixed and stirred to obtain a mixed solution A. On the other hand, 4.3 parts by weight of benzophenone (manufactured by Kanto Kagaku) as a photoinitiator and 0.4 part by weight of Michler's ketone (manufactured by Kanto Kagaku) as a photosensitizer were dissolved in 6.4 parts by weight of diethylene glycol dimethyl ether (DMDG) heated to 40 ° C. A mixed solution B was obtained. The mixed solution A and the mixed solution B were mixed and stirred to obtain a liquid resist.

(12) The above liquid resist is applied to both surfaces of the substrate which has been subjected to the catalyst nucleation treatment in the above (10) by using a roll coater and dried at 60 ° C. for 30 minutes to give a thickness of 30 μm. A resist layer is formed. Next, a photomask film having a conductor circuit pattern drawn thereon was placed on the resist layer and irradiated with ultraviolet rays of 400 mJ / cm ² for exposure. Then, after removing the photomask film, the resist layer is dissolved and developed with DMTG to form a plating resist on which a conductor circuit pattern portion is removed, and further exposed at 6000 mJ / cm ² with an ultra-high pressure mercury lamp. Then, heat treatment was performed at 100 ° C. for 1 hour and then at 150 ° C. for 3 hours to form a permanent resist 3 on the interlayer insulating layer 2 (see FIG. 9).

(13) Pre-plating treatment (specifically, activation of catalyst nuclei) is performed on the substrate on which the permanent resist 3 is formed in advance.
After that, primary plating was performed using an electroless copper-nickel alloy plating bath having the following composition to form a copper-nickel-phosphorus plating thin film having a thickness of about 1.7 μm on the resist non-forming portion. At this time, the temperature of the plating bath is 60 ° C,
The plating immersion time was 1 hour. Complexing agent: Na ₃ C ₆ H ₅ O ₇ : 0.23M (60g / l) Reducing agent: NaPH ₂ O ₂ · H ₂ O: 0.19M (20g / l) pH adjusting agent: NaOH: 0.75M (pH = 9.5) Stabilizer: Lead nitrate: 0.2 mM (80 ppm) Surfactant: 0.05 g / l Deposition rate is 1.7 μm / hour

(14) The substrate subjected to the primary plating treatment is pulled up from the plating bath, the plating bath adhering to the surface is washed away with water, and the substrate is treated with an acidic solution to give copper-nickel-phosphorus. The oxide film on the surface of the plated thin film was removed. After that, without performing Pd substitution, secondary plating is performed on the copper-nickel-phosphorus plating thin film using an electroless copper plating bath having the following composition, so that the outer layer conductor pattern 5 required as a conductor layer by the additive method is formed. And a via hole (BVH) 7 was formed (see FIG. 10). At this time, the temperature of the plating bath was 50 to 70 ° C., and the plating immersion time was 90 to 360 minutes. Metal salt ... CuSO ₄ .5H ₂ O: 8.6 mM Complexing agent ... TEA: 0.15M Reducing agent ... HCHO: 0.02M Others ... Stabilizers (bipyridyl, potassium ferrocyanide, etc.): Small amount deposition rate is 6 μm / hour

(15) After the conductor layer is formed by the additive method in this way, one surface of the substrate is polished by belt sander polishing using # 600 belt polishing paper to remove the surface of the permanent resist and the copper of the via hole. Polished until the top surface was aligned. Subsequently, buffing was carried out to remove the scratches caused by the belt sander (buffing only may be used). Then, the other surface was similarly polished to form a printed wiring board having smooth both surfaces.

(16) Then, from 8 g / l of copper sulfate, 0.6 g / l of nickel sulfate, 15 g / l of citric acid, 29 g / l of sodium hypophosphite, 31 g / l of boric acid, and 0.1 g / l of surfactant. Dipped in electroless plating solution of pH = 9, thickness 3μm
The roughened layer 11 made of the Cu-Ni-P alloy was formed (see FIG. 11). Then, by repeating the above steps (however, the lower interlayer insulating agent used has a viscosity of 1.5 Pa · s
I used the one. ), One more conductor layer was formed by the additive method, and the wiring layer was built up in this way to obtain a 6-layer multilayer printed wiring board.

(17) On the other hand, 60% by weight dissolved in DMDG
Cresol novolac type epoxy resin (manufactured by Nippon Kayaku)
46.67 g of a photosensitizing oligomer (molecular weight 4000) made by acrylate of 50% of epoxy groups, 80% by weight of bisphenol A type epoxy resin (Epicote 1001 made by Yuka Shell Co., Ltd.) dissolved in methyl ethyl ketone 15.0 g, imidazole curing Agent (Shikoku Kasei, trade name: 2E4MZ-CN) 1.6 g, polyvalent acrylic monomer (Nippon Kayaku, trade name: R604) 3 g, which is a photosensitive monomer, and polyvalent acrylic monomer (manufactured by Kyoeisha Chemical, trade name) : DPE6A) 1.5 g, a dispersion type antifoaming agent (manufactured by San Nopco, trade name: S-65) 0.71 g, and 2 g of benzophenone (manufactured by Kanto Chemical Co., Inc.) as a photoinitiator for these mixtures. Add 0.2 g of Michler's ketone (manufactured by Kanto Kagaku) as a photosensitizer to increase the viscosity.
A solder resist composition adjusted to 2.0 Pa · s at 25 ° C. was obtained. The viscosity is measured by a B-type viscometer (Tokyo Keiki, DVL
-B type) was according to rotor No. 4 for 60 rpm and rotor No. 3 for 6 rpm.

(18) A Pd catalyst was applied to the multilayer printed wiring board obtained in (16) above to activate the catalyst, and then copper sulfate 8 g / l, nickel sulfate 0.6 g / l, citric acid 15 g
/ L, sodium hypophosphite 29g / l, boric acid 31g /
1, a surface-active agent 0.1 g / l, and pH = 9 in an electroless plating bath to form a Cu-Ni-P alloy plating to form a roughened layer 11 on the conductor circuit surface. The solder resist composition having a thickness of 20 μm was applied to both surfaces of the multilayer printed wiring board. Then, after drying at 70 ℃ for 20 minutes and 70 ℃ for 30 minutes, it was exposed to UV light of 1000 mJ / cm ² and DM
TG development processing was performed. And then at 80 ℃ for 1 hour, 100 ℃
For 1 hour, at 120 ° C. for 1 hour, and at 150 ° C. for 3 hours to form a solder resist layer (thickness 20 μm) 14 having an open pad portion (opening diameter 200 μm).

(19) Next, the substrate on which the solder resist layer 14 is formed has a pH of 30 g / l of nickel chloride, 10 g / l of sodium hypophosphite, and 10 g / l of sodium citrate.
= 5 for immersion in an electroless nickel plating solution for 20 minutes to form a nickel plating layer 15 having a thickness of 5 μm in the opening. Further, the substrate was immersed in an electroless gold plating solution containing 2 g / l of potassium gold cyanide, 75 g / l of ammonium chloride, 50 g / l of sodium citrate, and 10 g / l of sodium hypophosphite at 93 ° C. for 23 seconds. By immersion, a 0.03 μm thick gold plating layer 16 was formed on the nickel plating layer 15.

(20) Then, solder paste is printed in the openings of the solder resist layer 14 and reflowed at 200 ° C. to form solder bumps 17, and a multilayer printed wiring board having the solder bumps 17 is manufactured ( (See Figure 12).

Comparative Example 1 A printed wiring board was manufactured in the same manner as in Example 1 except that the silicone oil of A was not added.

With respect to the printed wiring boards of Example 1 and Comparative Example 1 thus manufactured, the undulations on the surface of the wiring board were visually observed. Further, the fracture surface was observed with an electron microscope to confirm the presence of bubbles in the adhesive layer. Furthermore, a weather resistance test was performed on 10 printed wiring boards manufactured according to Example 1 and Comparative Example 1 under conditions of a temperature of 135 ° C., a humidity of 85%, a bias of 3.3 V, and a time of 48 hours. After this test, a short circuit between conductor circuits (whether there is continuity or not) was confirmed using a checker probe, and the occurrence rate of the short circuit was examined. The results are shown in Table 1.

[0065]

[Table 1]

(Example 2) [Preparation of adhesive B-2 for electroless plating] An alicyclic epoxy resin (manufactured by Dainippon Ink and Chemicals: EPICLON HP-7200) was used.
35 parts by weight, imidazole curing agent (Shikoku Kasei, trade name:
2E4MZ-CN) 2 parts by weight, a photosensitive monomer polyvalent acrylic monomer (Kyoeisha Chemical Co., Ltd., trade name: DPE6A) 6.0 parts by weight, polyvalent acrylic monomer (Nippon Kayaku Co., Ltd., trade name: R
604) 1.5 parts by weight, photoinitiator (manufactured by Ciba Geigy, trade name: Irgacure 907) 2 parts by weight, photosensitizer (manufactured by Nippon Kayaku, trade name: DETX-S) 0.2 parts by weight, silicone oil (Shin-Etsu Chemical) (Product name: KF-101) 8.75 parts by weight are mixed, and the average particle diameter of the epoxy resin particles (manufactured by Sanyo Kasei Co., Ltd .: polymer pole) is 3.0 μm.
Adhesion for electroless plating after mixing 10.3 parts by weight of the above and 3.09 parts by weight of the one having an average particle size of 0.5 μm while further adding 30 parts by weight of NMP and adjusting the viscosity to 7 Pa · s with a modisper stirrer. I got an agent.

[Manufacture of Printed Wiring Board] Solder in the same manner as in Example 1 except that the adhesive for electroless plating of B-2 was used and the following was used as the lower interlayer insulating agent. A multilayer printed wiring board having bumps was manufactured. 25% acrylated product of alicyclic epoxy resin (Dainippon Ink and Co., trade name: EPICLON HP-7200)
35 parts by weight, polyether sulfone (manufactured by Mitsui Toatsu, product name: PES1010P) 12 parts by weight, imidazole curing agent (manufactured by Shikoku Kasei, product name: 2E4MZ-CN) 2 parts by weight, and caprolactone modified tris which is a photosensitive monomer ( Acryloxyethyl) isocyanurate (Toagosei, trade name: Aronix M325) 4 parts by weight, benzophenone as a photoinitiator (Kanto Chemical) 2 parts by weight, Michler's ketone as a photosensitizer (Kanto Kagaku) 0.2 parts by weight Parts, and epoxy resin particles (manufactured by Sanyo Kasei, trade name:
12.0 parts by weight of polymer pole having an average particle size of 0.5 μm, silicone oil (manufactured by Shin-Etsu Chemical, trade name: KF-10
1) After mixing 8.75 parts by weight, the mixture was further mixed while adding NMP to obtain an interlayer resin insulating agent (lower layer) having a viscosity of 1.5 and 7.0 Pa · s.

Comparative Example 2 A printed wiring board was manufactured in the same manner as in Example 2 except that silicone oil was not added.

The printed wiring boards of Example 2 and Comparative Example 2 thus manufactured were subjected to a heat cycle test of 1000 times and 2000 times at -55 ° C to 125 ° C. At this time, it was confirmed whether or not cracks were generated in the adhesive layer for electroless plating located between the layers. The results are shown in Table 2.

[0070]

[Table 2]

Since the presence of silicone oil improves the tensile strength and the fracture elongation, it is considered that the occurrence of cracks in the adhesive for electroless plating between layers starting from the interface between the plating resist and the conductor circuit can be suppressed.

In this embodiment, the printed wiring board manufactured by the full additive method has been described.
The present invention can also be applied to a printed wiring board manufactured by the so-called semi-additive method or partly-additive method.

[0073]

As described above, according to the present invention, it is possible to prevent the surface of the adhesive layer for electroless plating from waviness and suppress the generation of bubbles. Further, according to the present invention, since the resin strength of the adhesive layer for electroless plating is improved, it is possible to suppress cracks in the adhesive layer for electroless plating that are generated by the heat cycle from the boundary between the plating resist and the conductor circuit. be able to.

[Brief description of drawings]

FIG. 1 is a diagram showing one step in manufacturing a printed wiring board according to the present invention.

FIG. 2 is a diagram showing one step in manufacturing a printed wiring board according to the present invention.

FIG. 3 is a diagram showing one step in manufacturing a printed wiring board according to the present invention.

FIG. 4 is a diagram showing one step in manufacturing the printed wiring board according to the present invention.

FIG. 5 is a diagram showing one step in manufacturing a printed wiring board according to the present invention.

FIG. 6 is a diagram showing one step in manufacturing a printed wiring board according to the present invention.

FIG. 7 is a diagram showing one step in manufacturing a printed wiring board according to the present invention.

FIG. 8 is a diagram showing a step in the production of the printed wiring board according to the present invention.

FIG. 9 is a diagram showing one step in manufacturing a printed wiring board according to the present invention.

FIG. 10 is a diagram showing a step in the production of the printed wiring board according to the present invention.

FIG. 11 is a diagram showing one step in manufacturing the printed wiring board according to the present invention.

FIG. 12 is a diagram showing a step in the production of the printed wiring board according to the present invention.

FIG. 13 is a spectrum diagram showing a measurement result of FT-IR.

FIG. 14 is a spectrum diagram showing a measurement result of ¹ H-NMR.

FIG. 15 is a spectrum diagram showing a measurement result of ¹³ C-NMR.

[Explanation of symbols]

1 substrate 2 Resin insulation layer 2a Insulating agent layer (interlayer insulating agent layer) 2b adhesive layer 3 plating resist 4 Inner layer conductor circuit (inner layer copper pattern) 5 Outer layer conductor circuit (outer layer copper pattern) 6 Via hole openings 7 Via hole (BVH) 8 copper foil 9 through holes 10 Filled resin (resin filler) 11 Roughened layer 14 Solder resist layer 15 Nickel plating layer 16 Gold plating layer 17 Solder bump

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-61-276875 (JP, A) JP-A-2-188992 (JP, A) JP-A-2-8281 (JP, A) JP-A-6- 240221 (JP, A) JP-A-9-80230 (JP, A) JP-A-8-34963 (JP, A) JP-A-7-331210 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C09J 4/00-201/10 H05K 3/38

Claims (5)

(57) [Claims] 1. A printed wiring comprising heat-resistant resin particles which are soluble in an acid or an oxidant and which have been cured and are dispersed in an uncured heat-resistant resin matrix which is hardly soluble in an acid or an oxidant by the curing treatment. In the adhesive for electroless plating used for a plate, the heat-resistant resin matrix contains more than 5% by weight and 5
An adhesive for electroless plating used in a printed wiring board, which contains 0% by weight or less of silicone oil. 2. The silicone oil has at least one functional group whose terminal group is selected from an epoxy group, a polyoxyalkylene group, an amino-containing group, a carboxy-containing group, a fatty acid-containing group and an alcohol-containing group. The adhesive for electroless plating according to claim 1, wherein the adhesive is modified with a base. 3. The adhesive for electroless plating according to claim 1, wherein the silicone oil is a polyether-modified silicone oil having a polyethylene oxide structure or a polypropylene oxide structure. 4. The adhesive for electroless plating according to claim 1, wherein the silicone oil has the following structural formula. [Chemical 1] 5. A printed wiring having a surface-roughened cured adhesive layer for electroless plating on a substrate, and a conductor circuit formed on the roughened surface of the adhesive layer surface. In the plate, the adhesive layer is formed by dispersing hardened heat-resistant resin particles soluble in an acid or an oxidant in an uncured heat-resistant resin matrix that is hardly soluble in an acid or an oxidant by a hardening treatment. A printed wiring board made of an adhesive, wherein the heat-resistant resin matrix contains silicon oil in an amount of more than 5% by weight and not more than 50% by weight .